This invention relates generally to fencing systems used to provide a secure enclosure for livestock, particularly horses. The present invention relates more specifically to the generally horizontal structural elements supported by a plurality of upright fence posts, and even more specifically to the incorporation of electrically conductive wires in the horizontal structural elements.
It is known to include electrically conductive wires in fence constructions for the confinement of livestock. Such systems generally include one or more electrically conductive wires. Representative examples of such systems are disclosed in U.S. Pat. Nos. 3,669,413 and 3,223,796. It has been recognized that bare wire systems, such as are disclosed in U.S. Pat. No. 3,669,413, are difficult for the livestock to see. The reaction of an animal to being shocked by such bare wire systems is unpredictable since the animal, unable to ascertain the location of the source of the shock, will often charge into a fence, rather than away from the fence, causing significant damage to the fence and injury to the animal. In addition to poor visibility, open wire systems also lack much aesthetic appeal beyond their low visibility.
It is also known to utilizing an electrically conductive wire in combination with a more visible horizontal structural element to enhance the likelihood that the animal, when shocked, will shy away from the fence. A particularly useful and more visible horizontal structural element is known to have a plurality of vertically spaced, high tensile-strength wires joined by intervening plastic webs. Representative examples of such systems are disclosed in U.S. Pat. Nos. 4,465,263; 4,864,107; 4,860,996; 4,881,721; 4,973,029; and 5,992,828. The electrically conductive wire was itself made somewhat more visible and less likely to injure an animal by coating the wire with an electrically conductive polymer to enhance the cross-sectional size of the wire. The electrically conductive wire was held in spaced relation to the webbed wire structure by special brackets designed for attachment to fence posts. While such systems provided improved performance over bare wire electrical fence systems, care had to be taken to ensure the tension in the electrically conductive wire closely matched the more visible structural elements so that the electrically conductive wire was suitably positioned. Further, from an aesthetic point of view, such systems were considered by some to be only a minor improvement over the previous bare wire systems.
There remains a need for a highly visible horizontal structural element for use in fencing that ensures the correct positioning of the electrically conductive wire. There also remains a need for a highly visible horizontal structural element for use in fencing that is aesthetically more pleasing so that it will be more readily accepted in areas having zoning regulations restricting the use of wire fencing.
In accordance with the present invention, a highly visible horizontal structural element for use in fencing is constructed as a single extruded webbing that has a plurality of longitudinally extending and substantially vertically aligned high-tensile strength core members, one of the core members comprising an electrically conductive wire. A solid plastic sheath encases each of the core members and a plurality of plastic webs extends between adjacent pairs of the core members with each of the plurality of plastic webs being joined to the plastic sheaths encasing the adjacent core members. The plastic sheath, which encases the electrically conductive wire core member, includes sufficient electrically conductive filler to permit passage of electrical charges from the electrically conductive wire to an outer surface of the sheath. The web joining the plastic sheath encasing the electrically conductive wire core member to the adjacent core member assures correct relative placement of the electrically conductive wire core member.
The webbing of the present invention can be made through the use of an extrusion mold including a plurality of inlet openings for receiving a plurality of longitudinally extending core members and an outlet opening generally having a cross-sectional shape of the webbing to be formed. A plurality of high-tensile strength core members, including a core member comprising an electrically conductive wire, are introduced into the inlet openings of the extrusion mold. At least two plasticizers or extruders of plastic are coupled to the extrusion mold to supply the plastic necessary to form the plastic sheath encasing each of the core members, and to form the plurality of plastic webs extending between adjacent pairs of the core members. The plastic extruder supplying the plastic sheath encasing the electrically conductive wire core member is supplied with a plastic including sufficient electrically conductive filler to permit passage of electrical charges through the plastic from the electrically conductive wire to an outer surface of the plastic sheath. The plastics are supplied by the plastic plasticizers at such rates that the plastic sheaths encasing the core members and the plurality of plastic webs joining the plastic sheaths are continuously formed as the core members pass through the extrusion mold and out the outlet opening.
Further, the extruded webbing of the present invention can have an outer surface that includes a pattern of ridges or grooves arranged to simulate a weathered wood surface. The patterned surface can be formed continuously with the extrusion of the webbing by embossing the pattern on the webbing by passing the extruded webbing between a pair of rollers situated adjacent to the outlet opening of the extrusion mold. At least one of the rollers is engraved with the desired pattern, which is reproduced in the webbing as it passes between the rollers. Alternatively, the patterned surface can be formed continuously with the extrusion of the webbing by etching the desired pattern on the webbing surface with a computer driven laser. The resulting pattern improves the aesthetic appeal of the webbing without detracting from its structural integrity.
Additional features and advantages of the invention are discussed below in conjunction with the illustrated preferred embodiments shown in the accompanying drawings.